Ribbon spool reversing mechanism



Nov. 15, 1966 w. D. LANDGRAF RIBB ON SPOOL REVERSING MECHANISM Filed Jan. 21, 1965 INVENTOR WALTER D. LANDGRAF ATTORNEYS United States Patent 3,285,383 RIBBON SPOOL REVERSING MECHANISM Walter David Landgraf, 4808 W. 96th Place,

Oak Lawn, Ill. Filed Jan. 21, 1965, Ser. No. 426,803 3 Claims. (Cl. 197-175) The present invention relates generally to spools for inked printing ribbons and, more particularly, to such spools having provisions for ribbon reversing mechanisms.

Ribbon spools for use with typewriters and various other types of business machines are generally provided with means for reversing the direction of the ribbon after it has been transferred, in response to actuation of the typewriter keys, from one of a pair of spools between which it is wound to the other, or take-up spool. Generally, the triggering mechanism for effecting the ribbon reversal is arranged to sense the absence of ribbon on the spool and simultaneously therewith to be tripped from one position to a second position, which automatically produces a reversal in the direction of the ribbon feed. The trigger element or mechanism is then returned to its initial or original position as the ribbon is wound upon the spool to which it is coupled.

In applicants Patent 3,093,231, there is disclosed a ribbon reversing mechanism of the above-described type wherein ribbon reversal is effected by a triggering element comprising a two-armed lever which is pivoted to tilt outwardly of the spool hub through an associated gap therein in the absence of ribbon on the spool. As described in the aforementioned patent, this motion is caused solely by the weight of the triggering element or arm, with the spool in horizontal position in the ribbon well of the typewriter.

Various other types of ribbon reversing mechanisms have required the use of leaf springs or coil springs attached to the reversing lever or triggering element to produce the desired motion when the ribbon unwinds completely from the spool. Thus, the gravity operated reversing trigger element of applicants above-mentioned prior patent constitutes a distinct improvement over the leaf or coil spring-operated or actuated lever, both in the reduction of the number of parts required and in the reduction in time and expense of assembly of the prior art reversing mechanisms. Nevertheless, in certain cases it is desirable to provide a more positive triggering actuation than is produced by gravity alone, and it is, accordingly, a primary object of the present invention to provide a ribbon spool reversing mechanism which is capable of such positive operation without the need for leaf springs or coil springs additional to the reversing lever.

In accordance with an embodiment of the present invention, a resilient projection incorporated in the flange of the ribbon spool is employed to maintain the triggering element in its proper position, while at the same time applying a continuous bias to the element to force it outwardly of the ribbon spool hub in the absence of ribbon on the spool. The resilient projection thus acts simultaneously as a positioning element and as a spring so that the triggering element or lever will always be in operating position when the ribbon is unwound from the spool. Further, since the projecting resilient element is an integral part of the spool, there is obviated any requirement for a separate spring or springs, with a consequent reduction in the cost of manufacturing the complete spool and of assembling the reversing trigger element in the spool. Also, in accordance with the present invention, the ribbon spool is provided with an integral anchoring post which is formed in the hub of the spool by eliminating material from the rim of the hub, the

Patented Nov. 15, 1966 ribbon being provided with a longitudinal slit adjacent its end such that it may be slipped over the post and thus secured in a simple and positive manner to the hub.

It is, therefore, a further object of the present invention to provide a spring biased ribbon spool reversing mechanism wherein the bias is provided by an integral part of the spool.

It is another object of the present invention to provide means for securing the ribbon end to the spool.

Some types of business machines and inked-printing machines are specifically designed for high speed opera tion. Where ribbon spools having gravity-operated reversing levers, i.e., a lever whose actuating motion is caused solely by its own weight, are employed in such machines it frequently happens that the centrifugal force on the lever, asccompanying the high angular velocity of the spool, is of suificient magnitude to overcome the effect of gravity, and hence to cause failure of the lever to operate. Such failure will ultimately result in absence of printing, as well as the distinct possibility that unwinding ribbon will jam the operation of the machine. Since it is a feature of the present invention that the reversing or triggering lever will continue to operate as a gravity-actuated device should the aforementioned projecting biasing member lose its resiliency, as by improper insertion of the lever into the spool or through subjection of the spool to use beyond the recommended period of replacement, it is desirable to provide protection against the above-mentioned possibility of high speed reversing failure.

To this end, the reversing lever of the present invention is fabricated to place its center of mass in or above the horizontal plane containing its pivot point for arcuate motion, when the lever is in its reverse-actuating position in the spool. Thereby, the centrifugal force acting upon the lever during high spool rotational velocities will not produce a moment about the lever pivot point in'a direction to counteract the moment produced by gravitational force on the lever, but rather in a direction to assist same.

It is therefore a further object of the present invention to provide positive actuation of the ribbon spool reversing lever during high speed operation even in the event of loss of resiliency of the lever biasing member.

The above and still further objects, features and attendant advantages of the present invention will become apparent from a consideration of the following detailed description of a specific embodiment thereof, especially when taken in conjunction with the accompanying drawings wherein;

FIGURE 1 is an exploded view in perspective of a typewriter spool assembly;

FIGURE 2 is an exploded perspective view of the spool associated with the assembly of FIGURE 1, with the ribbon end attached;

FIGURE 3 is a side elevational view in section of the ribbon spool illustrating the position of the triggering element in the absence of ribbon on the spool;

FIGURE 4 is a side elevational view of the spool in section illustrating the position of the triggering element with ribbon wound upon the spool;

FIGURE 5 is a section view of the spool taken through the lines 55 of FIGURE 4;

FIGURE 6 is a perspective view of the triggering ele- F ment of FIGURES 2-5;

FIGURE 7 is a section taken through lines 7-7 of FIGURE 4; and

FIGURE 8 is a view of the slit end of a typewriter ribbon.

Referring noW to the drawings wherein like reference numerals are used to refer to like component parts, the

acting as cover plates for the twin 'tuated and the carriage feeds.

reference numeral 10 denotes one cup and the reference number 11 another cup of a twin-cup inked ribbon cartridge. The specific type of cartridge or spool container is, however, not a part of the present invention, and is shown merely for illustrative purposes. The cups 10 and 11 each include bases 12, 13, cylindrical walls 14, 15, and axial openings 16, 17 in the bases, respectively. Identical spool elements 18 are provided for the cups 10 and 11.

The spool elements 18 include disk shaped flanges 20 cup inked ribbon cartridge. Flanges 20 have slightly smaller diameters than the inner diameters of cylindrical walls 14, 15, and are thus adapted to fit in a close but rotatable relation therein. Extending centrally from each flange 20 is a cylindrical hub 21 having means 24 for securing or attaching one end of a ribbon 22 (see also FIGURE 8) for winding about the hub.

To secure the ribbon 22.to the hub 21 each ribbon end is provided with a longitudinally extending slit or cut 23 through which the anchoring post 24 of hub 21 is inserted. That is, the ribbon end may simply be slipped over the anchoring post 24 such that the portion of ribbon below the cut 23 is positioned on one side of the post while the portion of ribbon above the cut 23 is positioned upon the other side of the post. Provision of an anchor post 24 in spool hub 21 is accomplished in a simple manher by providing a pair of parallel, longitudinal, closely spaced slots from the open or free end of the hub 21 extending toward the flange 20 of the spool element 18. In this manner, the spool is provided with a simple and inexpensive means for securing the ribbon to the hub. Similarly, the ribbon is provided with a simple and inexpensive means by which it may be attached to the hub for winding thereon. The ribbon slit may be centrally located with respect to the width of the ribbon, although this is purely examplary, and other shapes of opening may be preferred. The use of a slit has the advantage of ease in manufacture, in that a simple tool will suflice to accomplish the slit or cut and no ribbon material need be removed to form the opening. Moreover, the ribbon end conforms precisely to the hub 21 and no projections are formed as would be the case if the ribbon were folded over at its end or contained eyelets, hooks or the like as are required in conventional ribbon attachment.

The ribbon spools, in accordance with the present invention, are adapted to be inserted in the ribbon wells 30 of various commercial typewriters or other business machines to which are secured mechanisms 31 for actuating, i.e., driving, the spools when the typewriter keys are ac- The latter mechanism includes a pin 32 which extends into a mating opening 33 in a boss 34 located interiorly of hub 21 of the spool.

A radially projecting resilient element 40 is provided in the plane of the flange 20' extending approximately from the base of boss 34 toward the inner wall of hub 21. Preferably resilient element 40 is tapered at its free end. T provide the desired resiliency in projecting element 40, the spool element 18 may be formed or fabricated of a suitable plastic material or any other resilient material. Element 40 may be formed as an integral part of the flange by simply stamping out, or otherwise appropriately removing, a portion of the material of the flange during the manufacturing operation. Element 40 should be sufliciently narrow to permit a slight flexing with a marked tendency ,to return to its original position.

The triggering element 45 is preferably formed from a sheet of relatively stiff metal and may consist primarily of a two-armed lever, the arms 46, 47 extending substantially at right engles to one another.

Triggering element 45 is preferably fabricated to place nter; of gravity (or center of mass) in or above the containing its pivot point for arcuate motion, when r; element is in its ribbon reverse-actuating posith spool. This may be readily accomplished by tion of relative weight distributions in arms 4 46, 47 in accordance with the angle enclosed by the arms. For example, arm 47, which is the uppermost portion of the lever when the spool-lever assembly is installed in an inked-printing machine, may be made somewhat wider and longer than lower arm 46, but of the same thickness of material. Such a configuration is shown in exemplary form in FIGURE 6. Other triggering lever shapes for producing this desired effect will become immediately apparent since methods for exact determination and placement of center of mass of an object are well known in the art. The reason for such placement will be explained presently.

The constricted region 48 at the base of upper arm 47 is of slightly less width than the width of portion 50 of gap 55 adjacent the tip projecting element 40. A pair of ears 62, 63 extend from either side of constricting region 48, and are adapted to repose against associated protuberances 66, 67 on the undersurface of flange 20 (FIG. 3) when triggering element 45 is in its ribbon reverse-actuating position. For reasons which will become apparent, ears 62 and 63 extend beyond the maximum width of gap 55, while arm 47 is slightly wider than gap portion 50.

A portion of arm 47 is stamped outwardly at approximately the base of constricted region 48, in a direction opposite that in which lower arm 46 extends, to provide a slightly projecting tongue 57. The position of tongue 57 as well as the positions and relative dimensions of other portions of triggering element 45 become important in sofar as determination of mating portions in spool 18 are concerned, but are of no limiting importance in themselves except that tongue 57 be located with respect to projecting member 40 such that upon insertion of the lever into the spool, the lever is in reverse-actuating position with member 40 fully in the plane of flange portion 20, i.e., undepressed.

In coupling triggering element 45 and spool 18, arm 47 is pushed upwardly from the underside of flange 20 at the tip of projecting resilient element 40, the latter element having sufficient resiliency to permit such insertion without breaking, snapping or otherwise affecting its subsequent operation. When the constricted region 48 of arm 47 reaches the level of the gap adjacent the tip of projecting element 40, the triggering element will snap into position therein with the other arm 46 projecting radially outwardly at the underside of the flange. In this position, the tongue portion 57 of arm 47 rests upon the tip of the projecting resilient element 40, and by virtue of the position of the tip of the tongue relative to constricted region 48, the triggering element is tilted outwardly of the gap of hub 21. It will readily be seen that projecting element 40 maintains the triggering lever in its relatively coupled position in the spool with the tongue portion further preventing any possibility of disengagement thereof.

When the ribbon end is slipped over the anchoring post as previously described and the ribbon itself is wound about cylindrical hub 21, arm 47 is forced inwardly of the hub through an aligned gap 27 in the wall thereof, tongue portion 57 of arm 47 thus pressing downwardly on projecting resilient element 40 and forcing the tip thereof to flex slightly from the plane of the flange. Element 40 thus exerts a force on triggering lever 45, via the tongue portion thereof, in its tendency to return to its normal position in the plane of flange 20.

The relationship between the various elements of the spool is shown more clearly in the side elevational, partially sectioned view of FIGURE 4. In this figure, the spool is shown in the full spool condition: that is, with the ribbon wound completely about cylindrical hub 21 of the spool.

As previously discussed, the full spool is arranged to be inserted in the mating ribbon well of a commercial typewriter or other type of business machine. As the machine keys are actuated: that is, as typing proceeds, the ribbon is unwound from the spool on which it has initially been wound and proceeds to wind upon the takeup spool. Eventually, of course, the ribbon is completely unwound from spool element 18 permitting the reversing lever to pivot outwardly of the gap in the cylindrical hub 21 under the force exerted upon tongue portion 57 by projecting resilient element 40. There is thus provided a positive spring action to trigger the reversing mechanism of the typewriter or other machine, which is not subject to sticking as might possibly occur if the triggering lever were rendered movable by gravity alone. Moreover, it will be seen that the triggering lever operates without the need for auxiliary separate springs, which would add greatly to the cost and time of production. In addition, as previously described, the trigger lever is coupled with the spool without the need for rivets, screws, or other extraneous fastening devices.

Each time there is an absence of ribbon across the gap in hub 21, the triggering lever is actuated in a positive and reliable manner to effect ribbon feed reversal. When the ribbon rewinds about the cylindrical hub 21 of the spool element, the triggering lever is again forced inwardly of the hub, depressing projecting resilient element 40, and thus biasing the trigger for subsequent operation.

Because the center of mass of triggering lever 45 is, as previously discussed, arranged to be located in or above the plane containing its pivot point, which will normally coincide with the plane of flange 20, the lever 45 will continue to be effective to actuate reversal in the sense of rotation of the spool despite possible adverse environmental conditions. Principally, such adversities may arise as loss of resiliency of projecting element 40, caused by extensive use of the spool beyond the normal period during which it should be replaced, or subjection of the triggering lever to an extremely high magnitude of centrifugal force, produced by rotation of the spool when in use in high speed machines, or both. However, even in the highly unusual event that both such conditions may occur concurrently, a torque on the triggering lever about its pivot point would be produced by the centrifugal force, which may be viewed vectorially as acting through the center of mass of the lever. Such a torque would therefore aid in actuating triggering lever 45 to its spool-reversing position, until such time as the centrifugal force vector were parallel to the lever arm defined by a straight line connecting the center of mass and the pivot point of the lever, i.e., the vector sum of the centrifugal forces acting on a line intersecting both center of mass and pivot point. When reversal of spool rotation occurred, the triggering lever would, of course, be again forced inwardly of hub 21 as the ribbon was re-wound about the hub. It will be noted that if the center of mass of lever 45 were located below the horizontal plane containing the pivot point of the lever, the centrifugal force combined with retention of its depressed position by projecting element 40 would produce an upwardly directed torque on and movement of the lever, with consequent failure of reversal of spool rotation.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction, which are specifically illustrated and described, may be resorted to with out departing from the true spirit and scope of the invention. For

example, the particular shape of the reversing lever which has been described herein may be modified with appropriate changes being made in gap 50 surrounding the projecting element 40 as required. Further, the projecting element 40 need not lie specifically in the plane of flange 20, but may be offset therefrom or may constitute an entirely separate piece which is riveted or otherwise suitably fastened to the flange. The previously described configuration is, however, preferred because of its general simplicity, ease of fabrication and one-piece construction.

In view of these and other possible variations in the embodiment shown and described, it is desired that the present invention be limited only by the appended claims.

What I claim is:

1. A molded plastic ribbon spool comprising a substantially circular flange having a central axis, a tubular hub projecting axially from said flange, a longitudinal gap in the wall of said tubular hub, said flange including a resilient element formed by a cutout region in said flange adjacent and in alignment with said longitudinal gap, said resilient element being positioned normally in the plane of said flange and projecting radially within said cutout region from a point adjacent the axis of said flange toward the longitudinal gap in the wall of said hub; and a ribbon reversing lever having a pair of substantially perpendicular arms, one of said arms being dimensioned to permit passage through said longitudinal gap, said one of said arms including a projecting tongue arranged to contact and to depress said resilient element when said reversing lever is installed in position in said spool via said cutout region and last-named arm is confined within said gap by ribbon wound about said hub, said resilient element thereby biasing said lever to pivot outwardly of said hub and cooperating with said tongue to retain said lever in coupled pivotal relationship with said spool in the installed position.

2. The combination according to claim 1 wherein said hub includes a pair of longitudinal slots extending toward said flange, said slots defining a pin therebetween for securing said ribbon to said hub.

3. The combination according to claim 1 wherein the pivot point of said reversing lever is in the plane of said flange, and wherein the center of mass of said reversing lever is disposed above said plane when said lever is in said pivotal engagement with said flange, so that the centrifugal force on said lever accompanying rotation of said spool about said axis produces a torque about said pivot point in the direction of said outward travel of said lever.

References Cited by the Examiner UNITED STATES PATENTS 3,093,231 6/1963 Landgraf 197-175 3,112,020 11/1963 Bishop 197-175 3,195,708 7/1965 Biedinger 197-175 3,198,307 8/1965 Kloski 197-175 ROBERT E. PULFREY, Primary Examiner.

DAVID KLEIN, Examiner.

E. S. BURR, Assistant Examiner. 

1. A METHOD PLASTIC RIBBON SPOOL COMPRISING A SUBSTANITALLY CIRCULAR FLANGE HAVING A CENTRAL AXIS, A TUBULAR HUB PROJECTING AXIALLY FROM SAID FLANGE, A LONGITUDINAL GAP IN THE WALL OF SAID TUBULAR HUB, SAID FLANGE INCLUDING A RESILIENT ELEMENT FORMED BY A CUTOUT REGION IN SAID FLANGE ADJACENT AND IN ALIGNMENT WITH SAID LONGITUDINAL GAP, SAID RESILIENT ELEMENT BEING POSITIONED NORMALLY IN THE PLANE OF SAID FLANGE AND PROJECTING RADIALLY WITHIN SAID CUTOUT REGION FROM A POINT ADJACENT THE AXIS OF SAID FLANGE TOWARD THE LONGITUDINAL GAP IN THE WALL OF SAID HUB; AND A RIBBON REVERSING LEVER HAVING A PAIR OF SUBSTANTIALLY PERPENDICULAR ARMS, ONE OF SAID ARMS BEING DIMENSIONED TO PERMIT PASSAGE THROUGH SAID LONGITUDINAL GAP, SAID ONE OF SAID ARMS INCLUDING A PROJECTING TONGUE ARRANGED TO CONTACT AND TO DEPRESS SAID RESILIENT ELEMENT WHEN SAID REVERSING LEVER IS INSTALLED IN POSITION IN SAID SPOOL VIA SAID CUTOUT REGION AND LAST-NAMED ARM IN CONFINED WITHIN SAID GAP BY RIBBON WOUND ABOUT SAID HUB, SAID RESILIENT ELEMENT THEREBY BIASING SAID LEVER TO PIVOT OUTWARDLY OF SAID HUB AND COOPERATING WITH SAID TONGUE TO RETAIN SAID LEVER IN COUPLED PIVOTAL RELATIONSHIP WITH SAID SPOOL IN THE INSTALLED POSITION. 